Means for dressing grinding disks



March 29, 1938. A. RICKENMANN ET AL 2,112,679

MEANS FOR DRESSING GRINDING DISKS 3 Sheets-Sheet 1 vMarch 29, 1938. A. RICKENMANN ET Al.

MEANS FOR DRESSING GRINDING DI'SKS Filed Jari.y 6 1936 5 sheets-Sheet 2 www March 29, 1938. A A. RlcKENMANN Er A1. y 2,112,679

MEANS FOR DRESSING GRINDING DISKS Filed Ja'n. 6, 1936 3 Sheets-Sheet 3 amwnu Patented Mar; 29, 1938 UNITED. STATES PATENT. OFFICE Switzerland, assignors :enge Aktiengesellschaft, Zurich,

to Reishauer-Werkswitzerland- Application January 6, 1936, Serial No.- 57,812

6 Claims.

The present invention relates to a new and lm- .proved device for trueing proilled grinding wheels having' a plurality of annular grooves employed to produce a screw thread upon a workpiece, say taps, stock dies and so on.

The invention relates more particularly to a profiled rotary tool which has ,the converseprole of that of the grinding wheelin the form of one or more cylindrical screw threads and which tool is 'in engagement with the driving grinding wheeland returns after each complete revolution by an axial displacement to its initial position.

It has been proposed' to eiiect the axial displacement of the trueing roller by means of cams corresponding with the screw pitch, bearing against one anotherl over their cam surfaces of which cam one is xedly connected to a stationary part and the otherrotates with the roller, the roller being provided with a segmental recess at the point'of its periphery which tact with the'grinding wheel at the time the axial return movement is. to take place. The segmental recess allows the Aaxial displacement of the roller relatively to the grinding wheels.

The mainhlt'of the inventionv is to provide reliable means to ensure the uninterrupted rotation of the -roller while the axial displacement takes place, that-is, while the grinding wheel and the rollerv are temporarily out oi driving engage- -ment. n -Y A further object is the provision of va roller of a type aforesaid which is continuously rotated without the aid'of auxiliary means. 1

Other objects of the invention will in part be obvious and in part be pointed out hereinafter.

To, the attainment of theaforesaidobjects and ends the invention Astill further vresides in the novel details of construction, combination and arrangement of parts, all of which will be first fully described in' the following detailed description, and thenbe particularly pointed out in the appended clams,V reference being had to the accompanying drawings, in which:-

Fig. l is a vertical'section on the line g. 2. Fig. 2 is a horizontal section on the line 2 2 oi' Fig. 1.

Fig. 3 is -an `of1ig.2. y

. Fig. 4 is a further enlargement or a portion of Fig. 3 showing theslee'ves provided with grooves. Fig. 5 is a detail section and part elevation of the invention. f

In the drawings, in which like numerals of reference indicate like parts in all the ilgures, it will enlarged detail view of a portion be understood that the4 grinding is effected by means of groove-shaped grinding devices which are selected somewhat wider than the amount o f the width of the workpiece.

The profiling of the-disks is effected by rolling 5 thgfglgles/byfmeans ofn pressure' rollers $2 at a 'considerably reduced disk speed. -The roller is given the very best dimensions and speed'to attain the best results with a minimum of outlay for material which, owing to the kind of work to 10 be performed, has Ato be of very good quality. 'I'he values suitable are all within very narrow limits. In finding the value it has to be con- 'Sideredz The diameter ofthe roller cannot be less than the diameter of the pinions by which the rotary tool is journalled to obviate vibrations. On the other hand the diameter has to be kept as small as possible to reduce the cost, the material-neces- .sary being of a very high quality and veryexpensive. If the cost price of the l roller exceeds .a certaimupper limit, the whole method oi true-l ing the grinding wheels will n ot be economical. The diameter of the roller is lof* great importance too. In the method of trueing the grinding g5 wheels referred to, the roller is driven by the grinding wheel and the roller is displaced in axial direction by a coiled spring while the grinding wheel is out of contact with the roller. 'Ihe time in which this displacement can be performed depends on the speed at which the roller runs; there is normally very little time. The time for shifting the roller, moreover, depends on the breath of the segmental recess or gap of the rollers Tnis size cannot exceed a certain limit if good Work is to be performed by the roller. The desired result is te be attained only if all the said values are found so that at a vcertain speed the inertia of the roller is suicient to keep the roller inrotation while its recess passes over y40 the periphery of the grinding wheels. The best results are to be obtained by a peripheral speed of the roller of 0.4 to 0.9 meter per minute.4 At such a speedthe angle of the segmental recess is to be 58 to 67 degrees. roller is b est not less than and not more than millimeters. The diameter of the lroller may be below-the said minimum if by auxiliary means the mass, and therefore the inertia, of the roller is increasedI for instance, by attaching some 50 heavy metal. body of lead, or so on, to the roller. Aroller' having the dimensions as aforesaid and running at the speed mentioned will have sulcient inertia to rotate without an apprecia ble loss in speed while its' drive by the Srindin '5,3

'I'he diameter of the 45" wheel is interrupted. If a loss in speed. would occur the roller would have to beaccelerated by the grinding wheel when engaging` the roller again- The difference in the circumferential speed vleads to a very lrapid wear of the proled part of the roller. If, on the other hand, the cirhave to be made, or else a spring will be necessary whlchjwould be strong enough to perform the.

axial displacement of the roller in the very shortest time to obviate an impact of the roller on the profiled part of the grinding wheel. 'I'he use of a strong spring increases the friction of the cams and the wear thereof so that th'e accuracy decreases rapidly.

T he pressure rollers 92 are not provided .with closed profile grooves but are constructed asl singie screw threads, according to the desired proflle. The pressure roller must therefore carry out at each revolution an axial movement corresponding with the size of the pitch.

'I'he slide |99 carries a crank shaft |99x geared to a shaft Ill'x, as at |||Y, 'the shaft |||x having x the toothed wheel which meshes with a rack |z heldin a groove in the support v99 by a screw .asshown in Fig. 1. f

'Ihe rolling device is locatedattherafr pfsthe-m-.

machine.

By a slide 99 the "roller can be set against the disk. 'Ihe support .99 carries the mandrel 95 on which the actual rolling device runs. f

' By means 'of-the screw 99 the mandrel 95 is brought parallel to the disk axis and the support is clamped rmly by means of the nut 91. The bush 99 runs on balls 99 on the' mandrel 9 5. The pressure -roller itself' is firmly clamped 4on the bush |92, by means of the cap nut |99. By means of the spring |99 the whole is pressed against the counter cam |95 which is seated firmly onthe mandrel 95. In order that the cam can move easily on the counter curve, balls are interposed which are held by the cage |99. When the pressure roller is pressed against the'- slowly'rotating disk then the disk causes the roller to' rotate. By pressing against the cam the roller has simultaneously imparted thereto4 an axial movement which corresponds with the pitch of the cam and of the roller. When the roller has nearly made' a revolution it must again be returned. For this purpose the roller is provided with a recess |91.' The position of this recess relatively to the disk is identical with the position ofthe cam to' the counter cam .as regards the axial return move ment. When producing the pressure rollers or vcalm it is therefore always necessary to consider the positions of 'thecamtrackto theeambe.-

"ginningandtothereemoftherclleraccording means of the .screw |99.

fortheilrsttimeerwhenil,newproille'istobeY to a separate table. Thelmandrel 9| is clamped in the rolling 'support by -a clamping screw. VThe axial movement of for the purpose of adjustment in lle-rolled disksis effected by When using ne`w` disks rolled in al disk the diskmustbe turned tocyf lindrical shape. l'lor 'this purpose there is provided'on' the rolling support a smalllslide |99 which carries a diamond ||9 and which can be 4xnovedpastthledisklvymeansoftlietoothed wheel ||f|. The core or mandrel 95 is mounted within the supporting part 99 so as not to be rotatable -there` in. The core or mandrel 99 has a portion of reduced diameter at |29, and on this portion there is mounted the sleeve |2| which supports the balls 99. An extension |22 of the core or manl drel carries a sleeve |29.. The latter is ilxedly connected with the core'andshows' the cam |95 which vis intendedto cooperate with they companion cam |99 of the sleeve |25 through the interaction ofthe balls |29. The sleeve and the'LsA supporting4 ring 9| are carried by the slee've 99.

This sleeve 99 again rests on the-balls 99.

pressure rouer s2 1s1oeated withinthe'sieeve 172s andthe ring |99.4 .'I'he b'ush' 9|, the-.pressure roller 92 and the sleeve |25 are xedly securedlo.

on the sleeve 99 by 4means of the nut |99 and the spacer sleeve |92. A wedge 29 is located between -the 'roller 92 and the sleeve |25. Owing to this arrangement, the recess|9'|, Fig. S-,and'

the cam |99 will continuously remain in the same l5 relative position. At the free end ofthe' core or mandrel 95 a threaded portion 21'is'located ca rrying two nuts |29 which exert pressure against sleeve 99 by urging' the spring |94 against said sleeve, the .pressure being exerted through the 2il ary, all of the other elements are rotatable and 25 will rotate whenever the; rotary grinding disk .69

Ais pressed againstthe''roller-92.A

Q In order to make sure thatthe-balls' |29- Vduring -rttn'remain uniformly spaced 'from each other, a cage |99' is mounted on the sleeve |29, so

and this 'cage is provided 'on its-inner -face with.

grooves |92. A. portion of each'ball .projects into each groove.

Since. the grinding disk 59 is'provided with' grooves which are closed grooves, and-since the u -pressure roller 92 has va corresponding screw' thread, it isjobyieuslthat tmsfrener n must bel displaced..v in the direction of the arrow' I, the stretch of the displacement during each revolution corresponding tothescrew pitch. Upon'the.

termination of a'revolution, however, the pressureroller `must now'be "shifted back to the same extent. I br this purpose thecurves. |99 and |95- areshown.v The interposed balls |29 serve fox reducing the friction as in an ordinary ball bearing. Prom Fig. 4 it is apparent that the 'pressure 92 upon rotation of the'sleeve |25 in direc. tion of arrow 1I is `displaced in direction -of the .arrow I owing tothe inclined position of the cams |99, |99. AA' short time before the revolution iscompleted; the4 inclined surface |99 'o f the cam D0int of the'cam |95. The result is that due to the action' of the spring |90, the parts |25. 92,

'IIL |92, |99 and 99 are displaced in a'dlrectin opposite the direction of the arrow I a distance :l: which is-equal to the pitch of the screw thread.

This displacement is eifectedby the pressure roll 92. In order to make this possible, this'pressure roll must not. be in 'engagement with the grind- 0 ing darn at this instant. rmtms purposel the roll.92 has a recess |91 whichmakes it possible that the above mentioned elements 'can be-displaced. .With each'revohxtion of the pressure' roll,

therefore, the advance' movement inthe direc# tion of the arrow I, asdescribed abovegand -as c'ondioned by the cams.| 99, |99 is this' continuous advance movement of the pressure roll being of a value equal to the p itch and sudden jerk-like return movement then takes place owing 70 The slide u n mevea beek and rortnby mean.

aimera rapidly axially in the opposite direction during- .the remainder of said revolution to return the of a hand wheel and screw device 24 swivelling in a bearing 24! on slide 93 and threaded into a relatively stationary lug 241' on a part of the machine.

What I claim asl my invention is: 1. A grinding disk rotating on its aids, a rotatable pressure roller having a peripherallygrooved cutting surface provided with an interrupted portion, means by virtue of which said. roller may be brought into operative contact with said grinding disk to be rotated thereby, means to move said roller axially in one direction-during a part of a\ revolution thereof, and means to return saidroller to its initial operative positionduring the remainder of the revolution.

2. A grinding disk rotating on its axis, aroj -tatable pressure roller having a peripherally grooved cutting surface provided with an interrupted portion, means by virtue of which said roller may be brought into operative contact with A said grinding disk to be rotated thereby, and means to move said roller slowly in one direction along its axisduring the greater part of a revolutionI of the roller and to return the roller rapidly to its initial operative position along the axis during the remainder of said revolution.

3. A grinding disk rotating onits axis,V a rotat.- able pressure roller having a peripherally grooved cutting surface provided with an interrupted-portion, means by virtue of which said roller may be i brought into operative contact with said grinding disk to be'rotated thereby, and means to move said roller slowly in one-direction along its -axis during the greater part of a revolution of the roller and to return the roller rapidlyto its initial voperative position along the axis durin'gthe'remainder of said revolution, said last-named v means comprising a cam device and a ret spring acting on said roller,

4. A rotatable grinding disk having a grooved periphery to provide grinding edges, a pressure roller having in its periphery the negative grooves pre-rolled grinding roller to its -initial operative position, and means operatively disconnect said roller from contact with said grinding' disk during said return moved ment.

5. Arotatablegrinding disk having a grooved periphery to provide grinding edges,'a pressure roller having in its periphery the negative grooves and edges to those of said disk, .a slide adapted to be movable toward and from said grinding disk, a support pivotally adjustably mounted on said slide, means for mounting said roller in said support, means toadjust said support. to bring the axisl of saidy roller into parallelism with the axis of said'gri'nding disk, said roller being driven to rotate by contact with said grinding disk,

means by which said roller may be moved axially in onevdirection relatively slowly during aportion of the revolution of the roller and moved relatively rapidly axially in the opposite direction during. the-remainder of said revolution to return the roller fto its initial operative position, and

means operatively to disconnect said roller from contact with saidgrinding disk during said. re- -turn movement, said .last-named means residing in la recess formed in the periphery of said roller and extending the length thereof. I

6. A rotatable grinding disk having a grooved periphery 'to provide grinding'edgea a pressure roller having in its periphery thenegative grooves and edges to those of said disk, a slide adapted to be movable toward and from said grinding disk, a 1v support pivotally adjustably mounted on said slide, means for mounting' said roller in said suppom-means to adjust said support to bring the,

axisof said roller into parallelism with the axis of said grinding disk, said roller being-driven to rotate by contact with said grinding disk,

means by which said roller may be moved axially in one direction relatively slowly during a portion l of. the revolution of the roller and moved relative- 1y rapidly axially in the opposite direction during the remainder of said revolution to return the rollerito its initial operative position, means operatively to disconnect saidroller from contact with said grinding disk during said return movenient, said roller mounting means including a mandrel on which the roller is carried, and means toadjust the mandrel axially to accommodate disks.

ALFRED RICKENMANN.` EUGEN KREIS.- 

